Since metal fine particles each having a size of several nanometers to several hundred nanometers have unique optical characteristics, electrical characteristics, magnetic characteristics, catalytic action, and the like, the manufacturing method therefor has attracted attention as a key technology for developing new materials and substances in various fields such as industrial materials and medical supplies. In this description, metal fine particles are broadly divided into “nano particles” and “submicron particles” according to the size thereof. For convenience, by definition, the nano particles are particles each having a particle diameter not smaller than 1 nm and smaller than 100 nm, and the submicron particles are particles each having a particle diameter not smaller than 100 nm and smaller than 1 μm. As particles each having a particle diameter smaller than 1 nm, there are molecule-form metal particles (referred to as “clusters”), “atoms”, and the like.
As a method for manufacturing metal fine particles of a nanometer size, various methods are known. For example, Patent Document 1 describes a method in which high-output laser beams are condensed on a target disposed in a liquid to be treated using a lens and are irradiated, by which a colloidal solution containing nano particles is manufactured (this method is referred to as “laser ablation in solution”).
Also, for example, Patent Document 2 describes a method for making solid organic compounds particulate by laser beams.    Patent Document 1: Japanese Patent Laid-Open No. 2004-90081    Patent Document 2: Japanese Patent Laid-Open No. 2001-113159    Non-Patent Document 1: J. Phys. Chem. B 2003.107, 6920-6923